LANL, Los Alamos, New Mexico
LBNL, Berkeley, California
SAIC, Los Alamos, New Mexico
Funding: National Nuclear Security Administration of the US Department of Energy
The Dual-Axis Radiographic Hydrodynamic Test Facility (DARHT) at Los Alamos National Laboratory (LANL) consists of two linear induction accelerators oriented at right angles to each other. The DARHT First Axis has been successfully operated since 1999 and produces a 60 ns pulse with beam energy of 20 MeV and beam current of 1.9 kA. The DARHT Second Axis was successfully commissioned in May 2008 and produces a 1600 ns pulse with beam energy of 17.5 MeV and beam current of 2.1 kA. The Second Axis Injector uses a 16.5 cm diameter thermionic cathode with a 10 A/cm2 required current density to emit electrons into the accelerator. During the early Second Axis commissioning activities in 2006, deficiencies in the DARHT Second Axis Injector were found that prevented the injector cathode from meeting the required 10 A/cm2 current density. A comprehensive campaign was initiated to solve the injector cathode performance issues. This paper describes the deficiencies found and the solutions used to enable the DARHT Second Axis Injector to meet its requirements.
RadiaBeam, Marina del Rey
UCLA, Los Angeles, California
The fixed-field alternating-gradient (FFAG) betatron has emerged as a viable alternative to RF linacs as a source of high-energy radiation for industrial and security applications. RadiaBeam Technologies is currently developing an FFAG betatron with a novel induction core made with modern low-loss magnetic materials. The principle challenge in the project has been the design of the magnets. In this paper, we present the current status of the project, including results of the magnet design and testing.
LBNL, Berkeley, California
PPPL, Princeton, New Jersey
Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Recent changes to the NDCX beamline offer the promise of higher current compressed bunches, with correspondingly larger fluences, delivered to the target plane for ion-beam driven warm dense matter experiments. We report modeling and commissioning results of the upgraded NDCX beamline that includes a new induction bunching module with approximately twice the volt-seconds and greater tuning flexibility, combined with a longer neutralized drift compression channel.
LLNL, Livermore, California
TomoTherapy, Madison
CPAC, Madison
Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
We are developing a compact proton accelerator for cancer treatment by using the dielectric high-gradient insulator wall technology. The goal is to fit the compact dielectric wall proton therapy machine inside a conventional treatment room. To make the proton dielectric wall accelerator (DWA) compact requires a compact proton source capable of delivering protons in a sub-ns bunch. We are testing all the essential DWA components, including the compact proton source, on the First Accelerator System Test (FAST), which is designed to be taken apart and rebuilt many times to increase system performance by using improved components. The proton source being investigated currently is a surface flashover source. Five induction cells with HGI in the acceleration gaps are used to provide the 300-keV, 20-ns injector voltage for the proton injector. The physics design and the configuration of the injector and FAST will be presented.
USTC/NSRL, Hefei, Anhui
Funding: Work supported by National Natural Science Foundation of China (No.10175062 & 10575100).
The light pulse interval adjustment at Hefei Light Source (HLS) can be realized by using pulsed orbit bump technique, which requires for high-frequency repetitive, high magnetic flux density, short pulse kicker magnet system of which the power supply modulator should be specially designed. The technique of solid state modulator based on MOSFET is being developed in National synchrotron Radiation Laboratory (NSRL). In this paper, the design of a prototype of solid-state modulator with 20 MOSFETs in parallel is introduced, including triggering system, drive circuit, transformer configuration. The oscillation induced by parasitic capacitance and inductance is discussed. This prototype with four stage adder can achieve 100ns width power pulse output with 112A, 2.4 kV to the kicker.
OXFORDphysics, Oxford, Oxon
Imperial College of Science and Technology, Department of Physics, London
UMAN, Manchester
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
Brunel University, Middlesex
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
JAI, Oxford
Cockcroft Institute, Lancaster University, Lancaster
Manchester University, Manchester
Gray Cancer Institute, Northwood, Middlesex
Funding: EP/E032869/1
AMELA (Particle Accelerator for MEdicaL Applications) is a newly developed fixed field accelerator, which has capability for rapid beam acceleration, which is interesting for practical applications such as charged particle therapy. PAMELA aims to design a particle therapy facility using Non-Scaling FFAG technology, with a target beam repetition rate of 1kHz, which is far beyond that of conventional synchrotron. To realize the repetition rate, the key component is rf acceleration system. The combination of a high field gradient and a high duty factor is a significant challenge. In this paper, options for the system and the status of their development are presented.
KIT, Karlsruhe
FZK, Karlsruhe
University Erlangen-Nuernberg, Erlangen
Recently a new concept for automatically reducing magnetic field errors in superconductive undulators was proposed. According to this proposal the field errors are compensated by an array of coupled high temperature superconductor loops attached to the surface of the superconductive undulator. The field errors induce currents in the coupled type II-superconducting loops and, as a result, the magnetic field generated by these currents minimizes the field errors. In this paper the results of a first successful experimental test of this concept are described.
LANL, Los Alamos, New Mexico
LLNL, Livermore, California
NSTec, Los Alamos, New Mexico
Voss Scientific, Albuquerque, New Mexico
SAIC, Los Alamos, New Mexico
Funding: This work was supported by the US National Nuclear Security Agency and the US Department of Energy under contract W-7405-ENG-36.
The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 microsecond, which can be scraped off in a beam-head cleanup zone (BCUZ) before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and we will present data for the resulting beam transport and dynamics. We will also present beam stability data, and relate these to previous stability experiments at lower current and energy*.
* “Long-pulse beam stability experiments on the DARHT-II linear induction accelerator,” Carl Ekdahl, et al., IEEE Trans. Plasma. Sci. Vol. 34, 2006, pp. 460-466
LLNL, Livermore, California
TomoTherapy, Madison
TPL, Albuquerque, NM
CPAC, Madison
Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livvermore National Laboratory under Contract DE-AC52-07NA27344.
The dielectric wall accelerator* (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL) uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system is capable of accelerating any charge to mass ratio particle. Applications of high gradient proton and electron versions of this accelerator will be discussed. The status of the developmental new technologies that make the compact system possible will be reviewed. These include high gradient vacuum insulators, solid dielectric materials, photoconductive switches and compact proton sources.
*Patents pending.
PPPL, Princeton, New Jersey
LLNL, Livermore, California
LBNL, Berkeley, California
Voss Scientific, Albuquerque, New Mexico
Funding: Research supported by the US Department of Energy.
Neutralized drift compression offers an effective means for particle beam focusing and current amplification. In neutralized drift compression, a linear radial and longitudinal velocity drift is applied to a beam pulse, so that the beam pulse compresses as it drifts in the focusing section. The beam intensity can increase more than a factor of 100 in both the radial and longitudinal directions, totaling to more than a 10,000 times increase in the beam density during this process. The optimal configuration of focusing elements to mitigate the time-dependent focal plane is discussed in this paper. The self-electric and self-magnetic fields can prevent tight ballistic focusing and have to be neutralized by supplying neutralizing electrons. This paper presents a survey of the present numerical modeling techniques and theoretical understanding of plasma neutralization of intense particle beams. Investigations of intense beam pulse interaction with a background plasma have identified the operating regimes for stable and neutralized propagation of intense charged particle beams.
CAEP/IFP, Mainyang, Sichuan
TUB, Beijing
CAEP/IAE, Mianyang, Sichuan
It has been three decades since the research and development of key technologies and components started at the Institute of Fluid Physics, CAEP, for the linear induction accelerator (LIA). The first LIA was built in 1989 with beam parameters of 1.5 MeV, 3 kA and pulse width of 90 ns. Later the SG-I LIA (3.3 MeV, 2 kA, 90 ns) was developed for FEL in 1991. The first Linear Induction Accelerator X-Ray Facility (LIAXF, 10 MeV, 2 kA, 90 ns, spot size about 6 mm in diameter) was built in 1993 and upgraded to 12 MeV with higher performance (LIAXFU, 12 MeV, 2.5 kA, 90 ns, spot size about 4 mm in diameter) in 1995. The Dragon-I LIA with the best quality (20 MeV, 2.5 kA, 80 ns, spot size about 1 mm in diameter) in the world was finished in 2003. The smallest LIA with double pulses separated by 300 ns (MiniLIA, 200 keV, 1 A, 80 ns) was developed in 2007 for beam physics studies.
UMD, College Park, Maryland
Funding: * This work is funded by US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office.
The containment of beams in the longitudinal direction is fundamental to the operation of accelerators that circulate high intensity beams for long distances such as the University of Maryland Electron Ring (UMER); a scaled accelerator using low-energy electrons to model space-charge dynamics. The longitudinal space-charge forces in the beam, responsible for the expansion of the beam ends, cause a change in energy at the beam head/tail with respect to the main injected energy or flat-top part of the beam. This paper presents the first experimental results on using an induction cell to longitudinally focus the circulating beam within the UMER lattice for multiple turns.
Keywords: electron ring, focusing, induction cell.
UMD, College Park, Maryland
Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office.
Understanding the dynamics of the acceleration of high-intensity space-charge-dominated electron and ion beam is very important. Accelerating by steps a space-charge-dominated beam can be fundamentally different from beams at lower intensities, because at sufficiently high beam intensities the beam response to acceleration can drive to some unknown instabilities leading to a significant beam losses. This work analyses the acceleration of the University of Maryland Electron Ring (UMER) beam, i.e., high current, low-energy and space-charge-dominated electron beam which is applicable, on a scale basis, to a large class of other beam systems. We use the WARP particle-in-cell code to perform simulations that are compared with theoretical predictions and preliminary experimental results.